/* $Id: isdnloop.c,v 1.11.6.7 2001/11/11 19:54:31 kai Exp $
 *
 * ISDN low-level module implementing a dummy loop driver.
 *
 * Copyright 1997 by Fritz Elfert (fritz@isdn4linux.de)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 */

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/sched.h>
#include "isdnloop.h"

static char *isdnloop_id = "loop0";

MODULE_DESCRIPTION("ISDN4Linux: Pseudo Driver that simulates an ISDN card");
MODULE_AUTHOR("Fritz Elfert");
MODULE_LICENSE("GPL");
module_param(isdnloop_id, charp, 0);
MODULE_PARM_DESC(isdnloop_id, "ID-String of first card");

static int isdnloop_addcard(char *);

/*
 * Free queue completely.
 *
 * Parameter:
 *   card    = pointer to card struct
 *   channel = channel number
 */
static void
isdnloop_free_queue(isdnloop_card *card, int channel)
{
        struct sk_buff_head *queue = &card->bqueue[channel];

        skb_queue_purge(queue);
        card->sndcount[channel] = 0;
}

/*
 * Send B-Channel data to another virtual card.
 * This routine is called via timer-callback from isdnloop_pollbchan().
 *
 * Parameter:
 *   card = pointer to card struct.
 *   ch   = channel number (0-based)
 */
static void
isdnloop_bchan_send(isdnloop_card *card, int ch)
{
        isdnloop_card *rcard = card->rcard[ch];
        int rch = card->rch[ch], len, ack;
        struct sk_buff *skb;
        isdn_ctrl cmd;

        while (card->sndcount[ch]) {
                skb = skb_dequeue(&card->bqueue[ch]);
                if (skb) {
                        len = skb->len;
                        card->sndcount[ch] -= len;
                        ack = *(skb->head); /* used as scratch area */
                        cmd.driver = card->myid;
                        cmd.arg = ch;
                        if (rcard) {
                                rcard->interface.rcvcallb_skb(rcard->myid, rch, skb);
                        } else {
                                printk(KERN_WARNING "isdnloop: no rcard, skb dropped\n");
                                dev_kfree_skb(skb);

                        };
                        cmd.command = ISDN_STAT_BSENT;
                        cmd.parm.length = len;
                        card->interface.statcallb(&cmd);
                } else
                        card->sndcount[ch] = 0;
        }
}

/*
 * Send/Receive Data to/from the B-Channel.
 * This routine is called via timer-callback.
 * It schedules itself while any B-Channel is open.
 *
 * Parameter:
 *   data = pointer to card struct, set by kernel timer.data
 */
static void
isdnloop_pollbchan(struct timer_list *t)
{
        isdnloop_card *card = from_timer(card, t, rb_timer);
        unsigned long flags;

        if (card->flags & ISDNLOOP_FLAGS_B1ACTIVE)
                isdnloop_bchan_send(card, 0);
        if (card->flags & ISDNLOOP_FLAGS_B2ACTIVE)
                isdnloop_bchan_send(card, 1);
        if (card->flags & (ISDNLOOP_FLAGS_B1ACTIVE | ISDNLOOP_FLAGS_B2ACTIVE)) {
                /* schedule b-channel polling again */
                spin_lock_irqsave(&card->isdnloop_lock, flags);
                card->rb_timer.expires = jiffies + ISDNLOOP_TIMER_BCREAD;
                add_timer(&card->rb_timer);
                card->flags |= ISDNLOOP_FLAGS_RBTIMER;
                spin_unlock_irqrestore(&card->isdnloop_lock, flags);
        } else
                card->flags &= ~ISDNLOOP_FLAGS_RBTIMER;
}

/*
 * Parse ICN-type setup string and fill fields of setup-struct
 * with parsed data.
 *
 * Parameter:
 *   setup = setup string, format: [caller-id],si1,si2,[called-id]
 *   cmd   = pointer to struct to be filled.
 */
static void
isdnloop_parse_setup(char *setup, isdn_ctrl *cmd)
{
        char *t = setup;
        char *s = strchr(t, ',');

        *s++ = '\0';
        strlcpy(cmd->parm.setup.phone, t, sizeof(cmd->parm.setup.phone));
        s = strchr(t = s, ',');
        *s++ = '\0';
        if (!strlen(t))
                cmd->parm.setup.si1 = 0;
        else
                cmd->parm.setup.si1 = simple_strtoul(t, NULL, 10);
        s = strchr(t = s, ',');
        *s++ = '\0';
        if (!strlen(t))
                cmd->parm.setup.si2 = 0;
        else
                cmd->parm.setup.si2 =
                        simple_strtoul(t, NULL, 10);
        strlcpy(cmd->parm.setup.eazmsn, s, sizeof(cmd->parm.setup.eazmsn));
        cmd->parm.setup.plan = 0;
        cmd->parm.setup.screen = 0;
}

typedef struct isdnloop_stat {
        char *statstr;
        int command;
        int action;
} isdnloop_stat;
/* *INDENT-OFF* */
static isdnloop_stat isdnloop_stat_table[] = {
        {"BCON_",          ISDN_STAT_BCONN, 1}, /* B-Channel connected        */
        {"BDIS_",          ISDN_STAT_BHUP,  2}, /* B-Channel disconnected     */
        {"DCON_",          ISDN_STAT_DCONN, 0}, /* D-Channel connected        */
        {"DDIS_",          ISDN_STAT_DHUP,  0}, /* D-Channel disconnected     */
        {"DCAL_I",         ISDN_STAT_ICALL, 3}, /* Incoming call dialup-line  */
        {"DSCA_I",         ISDN_STAT_ICALL, 3}, /* Incoming call 1TR6-SPV     */
        {"FCALL",          ISDN_STAT_ICALL, 4}, /* Leased line connection up  */
        {"CIF",            ISDN_STAT_CINF,  5}, /* Charge-info, 1TR6-type     */
        {"AOC",            ISDN_STAT_CINF,  6}, /* Charge-info, DSS1-type     */
        {"CAU",            ISDN_STAT_CAUSE, 7}, /* Cause code                 */
        {"TEI OK",         ISDN_STAT_RUN,   0}, /* Card connected to wallplug */
        {"E_L1: ACT FAIL", ISDN_STAT_BHUP,  8}, /* Layer-1 activation failed  */
        {"E_L2: DATA LIN", ISDN_STAT_BHUP,  8}, /* Layer-2 data link lost     */
        {"E_L1: ACTIVATION FAILED",
         ISDN_STAT_BHUP,  8},         /* Layer-1 activation failed  */
        {NULL, 0, -1}
};
/* *INDENT-ON* */


/*
 * Parse Status message-strings from virtual card.
 * Depending on status, call statcallb for sending messages to upper
 * levels. Also set/reset B-Channel active-flags.
 *
 * Parameter:
 *   status  = status string to parse.
 *   channel = channel where message comes from.
 *   card    = card where message comes from.
 */
static void
isdnloop_parse_status(u_char *status, int channel, isdnloop_card *card)
{
        isdnloop_stat *s = isdnloop_stat_table;
        int action = -1;
        isdn_ctrl cmd;

        while (s->statstr) {
                if (!strncmp(status, s->statstr, strlen(s->statstr))) {
                        cmd.command = s->command;
                        action = s->action;
                        break;
                }
                s++;
        }
        if (action == -1)
                return;
        cmd.driver = card->myid;
        cmd.arg = channel;
        switch (action) {
        case 1:
                /* BCON_x */
                card->flags |= (channel) ?
                        ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE;
                break;
        case 2:
                /* BDIS_x */
                card->flags &= ~((channel) ?
                                 ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE);
                isdnloop_free_queue(card, channel);
                break;
        case 3:
                /* DCAL_I and DSCA_I */
                isdnloop_parse_setup(status + 6, &cmd);
                break;
        case 4:
                /* FCALL */
                sprintf(cmd.parm.setup.phone, "LEASED%d", card->myid);
                sprintf(cmd.parm.setup.eazmsn, "%d", channel + 1);
                cmd.parm.setup.si1 = 7;
                cmd.parm.setup.si2 = 0;
                cmd.parm.setup.plan = 0;
                cmd.parm.setup.screen = 0;
                break;
        case 5:
                /* CIF */
                strlcpy(cmd.parm.num, status + 3, sizeof(cmd.parm.num));
                break;
        case 6:
                /* AOC */
                snprintf(cmd.parm.num, sizeof(cmd.parm.num), "%d",
                         (int) simple_strtoul(status + 7, NULL, 16));
                break;
        case 7:
                /* CAU */
                status += 3;
                if (strlen(status) == 4)
                        snprintf(cmd.parm.num, sizeof(cmd.parm.num), "%s%c%c",
                                 status + 2, *status, *(status + 1));
                else
                        strlcpy(cmd.parm.num, status + 1, sizeof(cmd.parm.num));
                break;
        case 8:
                /* Misc Errors on L1 and L2 */
                card->flags &= ~ISDNLOOP_FLAGS_B1ACTIVE;
                isdnloop_free_queue(card, 0);
                cmd.arg = 0;
                cmd.driver = card->myid;
                card->interface.statcallb(&cmd);
                cmd.command = ISDN_STAT_DHUP;
                cmd.arg = 0;
                cmd.driver = card->myid;
                card->interface.statcallb(&cmd);
                cmd.command = ISDN_STAT_BHUP;
                card->flags &= ~ISDNLOOP_FLAGS_B2ACTIVE;
                isdnloop_free_queue(card, 1);
                cmd.arg = 1;
                cmd.driver = card->myid;
                card->interface.statcallb(&cmd);
                cmd.command = ISDN_STAT_DHUP;
                cmd.arg = 1;
                cmd.driver = card->myid;
                break;
        }
        card->interface.statcallb(&cmd);
}

/*
 * Store a cwcharacter into ringbuffer for reading from /dev/isdnctrl
 *
 * Parameter:
 *   card = pointer to card struct.
 *   c    = char to store.
 */
static void
isdnloop_putmsg(isdnloop_card *card, unsigned char c)
{
        ulong flags;

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        *card->msg_buf_write++ = (c == 0xff) ? '\n' : c;
        if (card->msg_buf_write == card->msg_buf_read) {
                if (++card->msg_buf_read > card->msg_buf_end)
                        card->msg_buf_read = card->msg_buf;
        }
        if (card->msg_buf_write > card->msg_buf_end)
                card->msg_buf_write = card->msg_buf;
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

/*
 * Poll a virtual cards message queue.
 * If there are new status-replies from the card, copy them to
 * ringbuffer for reading on /dev/isdnctrl and call
 * isdnloop_parse_status() for processing them. Watch for special
 * Firmware bootmessage and parse it, to get the D-Channel protocol.
 * If there are B-Channels open, initiate a timer-callback to
 * isdnloop_pollbchan().
 * This routine is called periodically via timer interrupt.
 *
 * Parameter:
 *   data = pointer to card struct
 */
static void
isdnloop_polldchan(struct timer_list *t)
{
        isdnloop_card *card = from_timer(card, t, st_timer);
        struct sk_buff *skb;
        int avail;
        int left;
        u_char c;
        int ch;
        unsigned long flags;
        u_char *p;
        isdn_ctrl cmd;

        skb = skb_dequeue(&card->dqueue);
        if (skb)
                avail = skb->len;
        else
                avail = 0;
        for (left = avail; left > 0; left--) {
                c = *skb->data;
                skb_pull(skb, 1);
                isdnloop_putmsg(card, c);
                card->imsg[card->iptr] = c;
                if (card->iptr < 59)
                        card->iptr++;
                if (!skb->len) {
                        avail++;
                        isdnloop_putmsg(card, '\n');
                        card->imsg[card->iptr] = 0;
                        card->iptr = 0;
                        if (card->imsg[0] == '0' && card->imsg[1] >= '0' &&
                            card->imsg[1] <= '2' && card->imsg[2] == ';') {
                                ch = (card->imsg[1] - '0') - 1;
                                p = &card->imsg[3];
                                isdnloop_parse_status(p, ch, card);
                        } else {
                                p = card->imsg;
                                if (!strncmp(p, "DRV1.", 5)) {
                                        printk(KERN_INFO "isdnloop: (%s) %s\n", CID, p);
                                        if (!strncmp(p + 7, "TC", 2)) {
                                                card->ptype = ISDN_PTYPE_1TR6;
                                                card->interface.features |= ISDN_FEATURE_P_1TR6;
                                                printk(KERN_INFO
                                                       "isdnloop: (%s) 1TR6-Protocol loaded and running\n", CID);
                                        }
                                        if (!strncmp(p + 7, "EC", 2)) {
                                                card->ptype = ISDN_PTYPE_EURO;
                                                card->interface.features |= ISDN_FEATURE_P_EURO;
                                                printk(KERN_INFO
                                                       "isdnloop: (%s) Euro-Protocol loaded and running\n", CID);
                                        }
                                        continue;

                                }
                        }
                }
        }
        if (avail) {
                cmd.command = ISDN_STAT_STAVAIL;
                cmd.driver = card->myid;
                cmd.arg = avail;
                card->interface.statcallb(&cmd);
        }
        if (card->flags & (ISDNLOOP_FLAGS_B1ACTIVE | ISDNLOOP_FLAGS_B2ACTIVE))
                if (!(card->flags & ISDNLOOP_FLAGS_RBTIMER)) {
                        /* schedule b-channel polling */
                        card->flags |= ISDNLOOP_FLAGS_RBTIMER;
                        spin_lock_irqsave(&card->isdnloop_lock, flags);
                        del_timer(&card->rb_timer);
                        card->rb_timer.expires = jiffies + ISDNLOOP_TIMER_BCREAD;
                        add_timer(&card->rb_timer);
                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                }
        /* schedule again */
        spin_lock_irqsave(&card->isdnloop_lock, flags);
        card->st_timer.expires = jiffies + ISDNLOOP_TIMER_DCREAD;
        add_timer(&card->st_timer);
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

/*
 * Append a packet to the transmit buffer-queue.
 *
 * Parameter:
 *   channel = Number of B-channel
 *   skb     = packet to send.
 *   card    = pointer to card-struct
 * Return:
 *   Number of bytes transferred, -E??? on error
 */
static int
isdnloop_sendbuf(int channel, struct sk_buff *skb, isdnloop_card *card)
{
        int len = skb->len;
        unsigned long flags;
        struct sk_buff *nskb;

        if (len > 4000) {
                printk(KERN_WARNING
                       "isdnloop: Send packet too large\n");
                return -EINVAL;
        }
        if (len) {
                if (!(card->flags & (channel ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE)))
                        return 0;
                if (card->sndcount[channel] > ISDNLOOP_MAX_SQUEUE)
                        return 0;
                spin_lock_irqsave(&card->isdnloop_lock, flags);
                nskb = dev_alloc_skb(skb->len);
                if (nskb) {
                        skb_copy_from_linear_data(skb,
                                                  skb_put(nskb, len), len);
                        skb_queue_tail(&card->bqueue[channel], nskb);
                        dev_kfree_skb(skb);
                } else
                        len = 0;
                card->sndcount[channel] += len;
                spin_unlock_irqrestore(&card->isdnloop_lock, flags);
        }
        return len;
}

/*
 * Read the messages from the card's ringbuffer
 *
 * Parameter:
 *   buf  = pointer to buffer.
 *   len  = number of bytes to read.
 *   user = flag, 1: called from userlevel 0: called from kernel.
 *   card = pointer to card struct.
 * Return:
 *   number of bytes actually transferred.
 */
static int
isdnloop_readstatus(u_char __user *buf, int len, isdnloop_card *card)
{
        int count;
        u_char __user *p;

        for (p = buf, count = 0; count < len; p++, count++) {
                if (card->msg_buf_read == card->msg_buf_write)
                        return count;
                if (put_user(*card->msg_buf_read++, p))
                        return -EFAULT;
                if (card->msg_buf_read > card->msg_buf_end)
                        card->msg_buf_read = card->msg_buf;
        }
        return count;
}

/*
 * Simulate a card's response by appending it to the cards
 * message queue.
 *
 * Parameter:
 *   card = pointer to card struct.
 *   s    = pointer to message-string.
 *   ch   = channel: 0 = generic messages, 1 and 2 = D-channel messages.
 * Return:
 *   0 on success, 1 on memory squeeze.
 */
static int
isdnloop_fake(isdnloop_card *card, char *s, int ch)
{
        struct sk_buff *skb;
        int len = strlen(s) + ((ch >= 0) ? 3 : 0);
        skb = dev_alloc_skb(len);
        if (!skb) {
                printk(KERN_WARNING "isdnloop: Out of memory in isdnloop_fake\n");
                return 1;
        }
        if (ch >= 0)
                sprintf(skb_put(skb, 3), "%02d;", ch);
        skb_put_data(skb, s, strlen(s));
        skb_queue_tail(&card->dqueue, skb);
        return 0;
}
/* *INDENT-OFF* */
static isdnloop_stat isdnloop_cmd_table[] = {
        {"BCON_R",         0,  1},      /* B-Channel connect        */
        {"BCON_I",         0, 17},      /* B-Channel connect ind    */
        {"BDIS_R",         0,  2},      /* B-Channel disconnect     */
        {"DDIS_R",         0,  3},      /* D-Channel disconnect     */
        {"DCON_R",         0, 16},      /* D-Channel connect        */
        {"DSCA_R",         0,  4},      /* Dial 1TR6-SPV     */
        {"DCAL_R",         0,  5},      /* Dial */
        {"EAZC",           0,  6},      /* Clear EAZ listener */
        {"EAZ",            0,  7},      /* Set EAZ listener */
        {"SEEAZ",          0,  8},      /* Get EAZ listener */
        {"MSN",            0,  9},      /* Set/Clear MSN listener */
        {"MSALL",          0, 10},      /* Set multi MSN listeners */
        {"SETSIL",         0, 11},      /* Set SI list     */
        {"SEESIL",         0, 12},      /* Get SI list     */
        {"SILC",           0, 13},      /* Clear SI list     */
        {"LOCK",           0, -1},      /* LOCK channel     */
        {"UNLOCK",         0, -1},      /* UNLOCK channel     */
        {"FV2ON",          1, 14},      /* Leased mode on               */
        {"FV2OFF",         1, 15},      /* Leased mode off              */
        {NULL, 0, -1}
};
/* *INDENT-ON* */


/*
 * Simulate an error-response from a card.
 *
 * Parameter:
 *   card = pointer to card struct.
 */
static void
isdnloop_fake_err(isdnloop_card *card)
{
        char buf[64];

        snprintf(buf, sizeof(buf), "E%s", card->omsg);
        isdnloop_fake(card, buf, -1);
        isdnloop_fake(card, "NAK", -1);
}

static u_char ctable_eu[] = {0x00, 0x11, 0x01, 0x12};
static u_char ctable_1t[] = {0x00, 0x3b, 0x01, 0x3a};

/*
 * Assemble a simplified cause message depending on the
 * D-channel protocol used.
 *
 * Parameter:
 *   card = pointer to card struct.
 *   loc  = location: 0 = local, 1 = remote.
 *   cau  = cause: 1 = busy, 2 = nonexistent callerid, 3 = no user responding.
 * Return:
 *   Pointer to buffer containing the assembled message.
 */
static char *
isdnloop_unicause(isdnloop_card *card, int loc, int cau)
{
        static char buf[6];

        switch (card->ptype) {
        case ISDN_PTYPE_EURO:
                sprintf(buf, "E%02X%02X", (loc) ? 4 : 2, ctable_eu[cau]);
                break;
        case ISDN_PTYPE_1TR6:
                sprintf(buf, "%02X44", ctable_1t[cau]);
                break;
        default:
                return "0000";
        }
        return buf;
}

/*
 * Release a virtual connection. Called from timer interrupt, when
 * called party did not respond.
 *
 * Parameter:
 *   card = pointer to card struct.
 *   ch   = channel (0-based)
 */
static void
isdnloop_atimeout(isdnloop_card *card, int ch)
{
        unsigned long flags;
        char buf[60];

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        if (card->rcard) {
                isdnloop_fake(card->rcard[ch], "DDIS_I", card->rch[ch] + 1);
                card->rcard[ch]->rcard[card->rch[ch]] = NULL;
                card->rcard[ch] = NULL;
        }
        isdnloop_fake(card, "DDIS_I", ch + 1);
        /* No user responding */
        sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 3));
        isdnloop_fake(card, buf, ch + 1);
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

/*
 * Wrapper for isdnloop_atimeout().
 */
static void
isdnloop_atimeout0(struct timer_list *t)
{
        isdnloop_card *card = from_timer(card, t, c_timer[0]);

        isdnloop_atimeout(card, 0);
}

/*
 * Wrapper for isdnloop_atimeout().
 */
static void
isdnloop_atimeout1(struct timer_list *t)
{
        isdnloop_card *card = from_timer(card, t, c_timer[1]);

        isdnloop_atimeout(card, 1);
}

/*
 * Install a watchdog for a user, not responding.
 *
 * Parameter:
 *   card = pointer to card struct.
 *   ch   = channel to watch for.
 */
static void
isdnloop_start_ctimer(isdnloop_card *card, int ch)
{
        unsigned long flags;

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        timer_setup(&card->c_timer[ch], ch ? isdnloop_atimeout1
                                           : isdnloop_atimeout0, 0);
        card->c_timer[ch].expires = jiffies + ISDNLOOP_TIMER_ALERTWAIT;
        add_timer(&card->c_timer[ch]);
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

/*
 * Kill a pending channel watchdog.
 *
 * Parameter:
 *   card = pointer to card struct.
 *   ch   = channel (0-based).
 */
static void
isdnloop_kill_ctimer(isdnloop_card *card, int ch)
{
        unsigned long flags;

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        del_timer(&card->c_timer[ch]);
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

static u_char si2bit[] = {0, 1, 0, 0, 0, 2, 0, 4, 0, 0};
static u_char bit2si[] = {1, 5, 7};

/*
 * Try finding a listener for an outgoing call.
 *
 * Parameter:
 *   card = pointer to calling card.
 *   p    = pointer to ICN-type setup-string.
 *   lch  = channel of calling card.
 *   cmd  = pointer to struct to be filled when parsing setup.
 * Return:
 *   0 = found match, alerting should happen.
 *   1 = found matching number but it is busy.
 *   2 = no matching listener.
 *   3 = found matching number but SI does not match.
 */
static int
isdnloop_try_call(isdnloop_card *card, char *p, int lch, isdn_ctrl *cmd)
{
        isdnloop_card *cc = cards;
        unsigned long flags;
        int ch;
        int num_match;
        int i;
        char *e;
        char nbuf[32];

        isdnloop_parse_setup(p, cmd);
        while (cc) {
                for (ch = 0; ch < 2; ch++) {
                        /* Exclude ourself */
                        if ((cc == card) && (ch == lch))
                                continue;
                        num_match = 0;
                        switch (cc->ptype) {
                        case ISDN_PTYPE_EURO:
                                for (i = 0; i < 3; i++)
                                        if (!(strcmp(cc->s0num[i], cmd->parm.setup.phone)))
                                                num_match = 1;
                                break;
                        case ISDN_PTYPE_1TR6:
                                e = cc->eazlist[ch];
                                while (*e) {
                                        sprintf(nbuf, "%s%c", cc->s0num[0], *e);
                                        if (!(strcmp(nbuf, cmd->parm.setup.phone)))
                                                num_match = 1;
                                        e++;
                                }
                        }
                        if (num_match) {
                                spin_lock_irqsave(&card->isdnloop_lock, flags);
                                /* channel idle? */
                                if (!(cc->rcard[ch])) {
                                        /* Check SI */
                                        if (!(si2bit[cmd->parm.setup.si1] & cc->sil[ch])) {
                                                spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                                                return 3;
                                        }
                                        /* ch is idle, si and number matches */
                                        cc->rcard[ch] = card;
                                        cc->rch[ch] = lch;
                                        card->rcard[lch] = cc;
                                        card->rch[lch] = ch;
                                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                                        return 0;
                                } else {
                                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                                        /* num matches, but busy */
                                        if (ch == 1)
                                                return 1;
                                }
                        }
                }
                cc = cc->next;
        }
        return 2;
}

/*
 * Depending on D-channel protocol and caller/called, modify
 * phone number.
 *
 * Parameter:
 *   card   = pointer to card struct.
 *   phone  = pointer phone number.
 *   caller = flag: 1 = caller, 0 = called.
 * Return:
 *   pointer to new phone number.
 */
static char *
isdnloop_vstphone(isdnloop_card *card, char *phone, int caller)
{
        int i;
        static char nphone[30];

        if (!card) {
                printk("BUG!!!\n");
                return "";
        }
        switch (card->ptype) {
        case ISDN_PTYPE_EURO:
                if (caller) {
                        for (i = 0; i < 2; i++)
                                if (!(strcmp(card->s0num[i], phone)))
                                        return phone;
                        return card->s0num[0];
                }
                return phone;
                break;
        case ISDN_PTYPE_1TR6:
                if (caller) {
                        sprintf(nphone, "%s%c", card->s0num[0], phone[0]);
                        return nphone;
                } else
                        return &phone[strlen(phone) - 1];
                break;
        }
        return "";
}

/*
 * Parse an ICN-type command string sent to the 'card'.
 * Perform misc. actions depending on the command.
 *
 * Parameter:
 *   card = pointer to card struct.
 */
static void
isdnloop_parse_cmd(isdnloop_card *card)
{
        char *p = card->omsg;
        isdn_ctrl cmd;
        char buf[60];
        isdnloop_stat *s = isdnloop_cmd_table;
        int action = -1;
        int i;
        int ch;

        if ((card->omsg[0] != '0') && (card->omsg[2] != ';')) {
                isdnloop_fake_err(card);
                return;
        }
        ch = card->omsg[1] - '0';
        if ((ch < 0) || (ch > 2)) {
                isdnloop_fake_err(card);
                return;
        }
        p += 3;
        while (s->statstr) {
                if (!strncmp(p, s->statstr, strlen(s->statstr))) {
                        action = s->action;
                        if (s->command && (ch != 0)) {
                                isdnloop_fake_err(card);
                                return;
                        }
                        break;
                }
                s++;
        }
        if (action == -1)
                return;
        switch (action) {
        case 1:
                /* 0x;BCON_R */
                if (card->rcard[ch - 1]) {
                        isdnloop_fake(card->rcard[ch - 1], "BCON_I",
                                      card->rch[ch - 1] + 1);
                        isdnloop_fake(card, "BCON_C", ch);
                }
                break;
        case 17:
                /* 0x;BCON_I */
                if (card->rcard[ch - 1]) {
                        isdnloop_fake(card->rcard[ch - 1], "BCON_C",
                                      card->rch[ch - 1] + 1);
                }
                break;
        case 2:
                /* 0x;BDIS_R */
                isdnloop_fake(card, "BDIS_C", ch);
                if (card->rcard[ch - 1]) {
                        isdnloop_fake(card->rcard[ch - 1], "BDIS_I",
                                      card->rch[ch - 1] + 1);
                }
                break;
        case 16:
                /* 0x;DCON_R */
                isdnloop_kill_ctimer(card, ch - 1);
                if (card->rcard[ch - 1]) {
                        isdnloop_kill_ctimer(card->rcard[ch - 1], card->rch[ch - 1]);
                        isdnloop_fake(card->rcard[ch - 1], "DCON_C",
                                      card->rch[ch - 1] + 1);
                        isdnloop_fake(card, "DCON_C", ch);
                }
                break;
        case 3:
                /* 0x;DDIS_R */
                isdnloop_kill_ctimer(card, ch - 1);
                if (card->rcard[ch - 1]) {
                        isdnloop_kill_ctimer(card->rcard[ch - 1], card->rch[ch - 1]);
                        isdnloop_fake(card->rcard[ch - 1], "DDIS_I",
                                      card->rch[ch - 1] + 1);
                        card->rcard[ch - 1] = NULL;
                }
                isdnloop_fake(card, "DDIS_C", ch);
                break;
        case 4:
                /* 0x;DSCA_Rdd,yy,zz,oo */
                if (card->ptype != ISDN_PTYPE_1TR6) {
                        isdnloop_fake_err(card);
                        return;
                }
                /* Fall through */
        case 5:
                /* 0x;DCAL_Rdd,yy,zz,oo */
                p += 6;
                switch (isdnloop_try_call(card, p, ch - 1, &cmd)) {
                case 0:
                        /* Alerting */
                        sprintf(buf, "D%s_I%s,%02d,%02d,%s",
                                (action == 4) ? "SCA" : "CAL",
                                isdnloop_vstphone(card, cmd.parm.setup.eazmsn, 1),
                                cmd.parm.setup.si1,
                                cmd.parm.setup.si2,
                                isdnloop_vstphone(card->rcard[ch - 1],
                                                  cmd.parm.setup.phone, 0));
                        isdnloop_fake(card->rcard[ch - 1], buf, card->rch[ch - 1] + 1);
                        /* Fall through */
                case 3:
                        /* si1 does not match, don't alert but start timer */
                        isdnloop_start_ctimer(card, ch - 1);
                        break;
                case 1:
                        /* Remote busy */
                        isdnloop_fake(card, "DDIS_I", ch);
                        sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 1));
                        isdnloop_fake(card, buf, ch);
                        break;
                case 2:
                        /* No such user */
                        isdnloop_fake(card, "DDIS_I", ch);
                        sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 2));
                        isdnloop_fake(card, buf, ch);
                        break;
                }
                break;
        case 6:
                /* 0x;EAZC */
                card->eazlist[ch - 1][0] = '\0';
                break;
        case 7:
                /* 0x;EAZ */
                p += 3;
                if (strlen(p) >= sizeof(card->eazlist[0]))
                        break;
                strcpy(card->eazlist[ch - 1], p);
                break;
        case 8:
                /* 0x;SEEAZ */
                sprintf(buf, "EAZ-LIST: %s", card->eazlist[ch - 1]);
                isdnloop_fake(card, buf, ch + 1);
                break;
        case 9:
                /* 0x;MSN */
                break;
        case 10:
                /* 0x;MSNALL */
                break;
        case 11:
                /* 0x;SETSIL */
                p += 6;
                i = 0;
                while (strchr("0157", *p)) {
                        if (i)
                                card->sil[ch - 1] |= si2bit[*p - '0'];
                        i = (*p++ == '0');
                }
                if (*p)
                        isdnloop_fake_err(card);
                break;
        case 12:
                /* 0x;SEESIL */
                sprintf(buf, "SIN-LIST: ");
                p = buf + 10;
                for (i = 0; i < 3; i++)
                        if (card->sil[ch - 1] & (1 << i))
                                p += sprintf(p, "%02d", bit2si[i]);
                isdnloop_fake(card, buf, ch + 1);
                break;
        case 13:
                /* 0x;SILC */
                card->sil[ch - 1] = 0;
                break;
        case 14:
                /* 00;FV2ON */
                break;
        case 15:
                /* 00;FV2OFF */
                break;
        }
}

/*
 * Put command-strings into the of the 'card'. In reality, execute them
 * right in place by calling isdnloop_parse_cmd(). Also copy every
 * command to the read message ringbuffer, preceding it with a '>'.
 * These mesagges can be read at /dev/isdnctrl.
 *
 * Parameter:
 *   buf  = pointer to command buffer.
 *   len  = length of buffer data.
 *   user = flag: 1 = called form userlevel, 0 called from kernel.
 *   card = pointer to card struct.
 * Return:
 *   number of bytes transferred (currently always equals len).
 */
static int
isdnloop_writecmd(const u_char *buf, int len, int user, isdnloop_card *card)
{
        int xcount = 0;
        int ocount = 1;
        isdn_ctrl cmd;

        while (len) {
                int count = len;
                u_char *p;
                u_char msg[0x100];

                if (count > 255)
                        count = 255;
                if (user) {
                        if (copy_from_user(msg, buf, count))
                                return -EFAULT;
                } else
                        memcpy(msg, buf, count);
                isdnloop_putmsg(card, '>');
                for (p = msg; count > 0; count--, p++) {
                        len--;
                        xcount++;
                        isdnloop_putmsg(card, *p);
                        card->omsg[card->optr] = *p;
                        if (*p == '\n') {
                                card->omsg[card->optr] = '\0';
                                card->optr = 0;
                                isdnloop_parse_cmd(card);
                                if (len) {
                                        isdnloop_putmsg(card, '>');
                                        ocount++;
                                }
                        } else {
                                if (card->optr < 59)
                                        card->optr++;
                        }
                        ocount++;
                }
        }

        cmd.command = ISDN_STAT_STAVAIL;
        cmd.driver = card->myid;
        cmd.arg = ocount;
        card->interface.statcallb(&cmd);
        return xcount;
}

/*
 * Delete card's pending timers, send STOP to linklevel
 */
static void
isdnloop_stopcard(isdnloop_card *card)
{
        unsigned long flags;
        isdn_ctrl cmd;

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        if (card->flags & ISDNLOOP_FLAGS_RUNNING) {
                card->flags &= ~ISDNLOOP_FLAGS_RUNNING;
                del_timer(&card->st_timer);
                del_timer(&card->rb_timer);
                del_timer(&card->c_timer[0]);
                del_timer(&card->c_timer[1]);
                cmd.command = ISDN_STAT_STOP;
                cmd.driver = card->myid;
                card->interface.statcallb(&cmd);
        }
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
}

/*
 * Stop all cards before unload.
 */
static void
isdnloop_stopallcards(void)
{
        isdnloop_card *p = cards;

        while (p) {
                isdnloop_stopcard(p);
                p = p->next;
        }
}

/*
 * Start a 'card'. Simulate card's boot message and set the phone
 * number(s) of the virtual 'S0-Interface'. Install D-channel
 * poll timer.
 *
 * Parameter:
 *   card  = pointer to card struct.
 *   sdefp = pointer to struct holding ioctl parameters.
 * Return:
 *   0 on success, -E??? otherwise.
 */
static int
isdnloop_start(isdnloop_card *card, isdnloop_sdef *sdefp)
{
        unsigned long flags;
        isdnloop_sdef sdef;
        int i;

        if (card->flags & ISDNLOOP_FLAGS_RUNNING)
                return -EBUSY;
        if (copy_from_user((char *) &sdef, (char *) sdefp, sizeof(sdef)))
                return -EFAULT;

        for (i = 0; i < 3; i++) {
                if (!memchr(sdef.num[i], 0, sizeof(sdef.num[i])))
                        return -EINVAL;
        }

        spin_lock_irqsave(&card->isdnloop_lock, flags);
        switch (sdef.ptype) {
        case ISDN_PTYPE_EURO:
                if (isdnloop_fake(card, "DRV1.23EC-Q.931-CAPI-CNS-BASIS-20.02.96",
                                  -1)) {
                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                        return -ENOMEM;
                }
                card->sil[0] = card->sil[1] = 4;
                if (isdnloop_fake(card, "TEI OK", 0)) {
                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                        return -ENOMEM;
                }
                for (i = 0; i < 3; i++) {
                        strlcpy(card->s0num[i], sdef.num[i],
                                sizeof(card->s0num[0]));
                }
                break;
        case ISDN_PTYPE_1TR6:
                if (isdnloop_fake(card, "DRV1.04TC-1TR6-CAPI-CNS-BASIS-29.11.95",
                                  -1)) {
                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                        return -ENOMEM;
                }
                card->sil[0] = card->sil[1] = 4;
                if (isdnloop_fake(card, "TEI OK", 0)) {
                        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                        return -ENOMEM;
                }
                strlcpy(card->s0num[0], sdef.num[0], sizeof(card->s0num[0]));
                card->s0num[1][0] = '\0';
                card->s0num[2][0] = '\0';
                break;
        default:
                spin_unlock_irqrestore(&card->isdnloop_lock, flags);
                printk(KERN_WARNING "isdnloop: Illegal D-channel protocol %d\n",
                       sdef.ptype);
                return -EINVAL;
        }
        timer_setup(&card->rb_timer, isdnloop_pollbchan, 0);
        timer_setup(&card->st_timer, isdnloop_polldchan, 0);
        card->st_timer.expires = jiffies + ISDNLOOP_TIMER_DCREAD;
        add_timer(&card->st_timer);
        card->flags |= ISDNLOOP_FLAGS_RUNNING;
        spin_unlock_irqrestore(&card->isdnloop_lock, flags);
        return 0;
}

/*
 * Main handler for commands sent by linklevel.
 */
static int
isdnloop_command(isdn_ctrl *c, isdnloop_card *card)
{
        ulong a;
        int i;
        char cbuf[80];
        isdn_ctrl cmd;
        isdnloop_cdef cdef;

        switch (c->command) {
        case ISDN_CMD_IOCTL:
                memcpy(&a, c->parm.num, sizeof(ulong));
                switch (c->arg) {
                case ISDNLOOP_IOCTL_DEBUGVAR:
                        return (ulong) card;
                case ISDNLOOP_IOCTL_STARTUP:
                        return isdnloop_start(card, (isdnloop_sdef *) a);
                        break;
                case ISDNLOOP_IOCTL_ADDCARD:
                        if (copy_from_user((char *)&cdef,
                                           (char *)a,
                                           sizeof(cdef)))
                                return -EFAULT;
                        return isdnloop_addcard(cdef.id1);
                        break;
                case ISDNLOOP_IOCTL_LEASEDCFG:
                        if (a) {
                                if (!card->leased) {
                                        card->leased = 1;
                                        while (card->ptype == ISDN_PTYPE_UNKNOWN)
                                                schedule_timeout_interruptible(10);
                                        schedule_timeout_interruptible(10);
                                        sprintf(cbuf, "00;FV2ON\n01;EAZ1\n02;EAZ2\n");
                                        i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                                        printk(KERN_INFO
                                               "isdnloop: (%s) Leased-line mode enabled\n",
                                               CID);
                                        cmd.command = ISDN_STAT_RUN;
                                        cmd.driver = card->myid;
                                        cmd.arg = 0;
                                        card->interface.statcallb(&cmd);
                                }
                        } else {
                                if (card->leased) {
                                        card->leased = 0;
                                        sprintf(cbuf, "00;FV2OFF\n");
                                        i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                                        printk(KERN_INFO
                                               "isdnloop: (%s) Leased-line mode disabled\n",
                                               CID);
                                        cmd.command = ISDN_STAT_RUN;
                                        cmd.driver = card->myid;
                                        cmd.arg = 0;
                                        card->interface.statcallb(&cmd);
                                }
                        }
                        return 0;
                default:
                        return -EINVAL;
                }
                break;
        case ISDN_CMD_DIAL:
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                if (card->leased)
                        break;
                if ((c->arg & 255) < ISDNLOOP_BCH) {
                        char *p;
                        char dcode[4];

                        a = c->arg;
                        p = c->parm.setup.phone;
                        if (*p == 's' || *p == 'S') {
                                /* Dial for SPV */
                                p++;
                                strcpy(dcode, "SCA");
                        } else
                                /* Normal Dial */
                                strcpy(dcode, "CAL");
                        snprintf(cbuf, sizeof(cbuf),
                                 "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
                                 dcode, p, c->parm.setup.si1,
                                 c->parm.setup.si2, c->parm.setup.eazmsn);
                        i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                }
                break;
        case ISDN_CMD_ACCEPTD:
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                if (c->arg < ISDNLOOP_BCH) {
                        a = c->arg + 1;
                        cbuf[0] = 0;
                        switch (card->l2_proto[a - 1]) {
                        case ISDN_PROTO_L2_X75I:
                                sprintf(cbuf, "%02d;BX75\n", (int) a);
                                break;
#ifdef CONFIG_ISDN_X25
                        case ISDN_PROTO_L2_X25DTE:
                                sprintf(cbuf, "%02d;BX2T\n", (int) a);
                                break;
                        case ISDN_PROTO_L2_X25DCE:
                                sprintf(cbuf, "%02d;BX2C\n", (int) a);
                                break;
#endif
                        case ISDN_PROTO_L2_HDLC:
                                sprintf(cbuf, "%02d;BTRA\n", (int) a);
                                break;
                        }
                        if (strlen(cbuf))
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        sprintf(cbuf, "%02d;DCON_R\n", (int) a);
                        i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                }
                break;
        case ISDN_CMD_ACCEPTB:
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                if (c->arg < ISDNLOOP_BCH) {
                        a = c->arg + 1;
                        switch (card->l2_proto[a - 1]) {
                        case ISDN_PROTO_L2_X75I:
                                sprintf(cbuf, "%02d;BCON_R,BX75\n", (int) a);
                                break;
#ifdef CONFIG_ISDN_X25
                        case ISDN_PROTO_L2_X25DTE:
                                sprintf(cbuf, "%02d;BCON_R,BX2T\n", (int) a);
                                break;
                        case ISDN_PROTO_L2_X25DCE:
                                sprintf(cbuf, "%02d;BCON_R,BX2C\n", (int) a);
                                break;
#endif
                        case ISDN_PROTO_L2_HDLC:
                                sprintf(cbuf, "%02d;BCON_R,BTRA\n", (int) a);
                                break;
                        default:
                                sprintf(cbuf, "%02d;BCON_R\n", (int) a);
                        }
                        printk(KERN_DEBUG "isdnloop writecmd '%s'\n", cbuf);
                        i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        break;
                case ISDN_CMD_HANGUP:
                        if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                                return -ENODEV;
                        if (c->arg < ISDNLOOP_BCH) {
                                a = c->arg + 1;
                                sprintf(cbuf, "%02d;BDIS_R\n%02d;DDIS_R\n", (int) a, (int) a);
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        }
                        break;
                case ISDN_CMD_SETEAZ:
                        if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                                return -ENODEV;
                        if (card->leased)
                                break;
                        if (c->arg < ISDNLOOP_BCH) {
                                a = c->arg + 1;
                                if (card->ptype == ISDN_PTYPE_EURO) {
                                        sprintf(cbuf, "%02d;MS%s%s\n", (int) a,
                                                c->parm.num[0] ? "N" : "ALL", c->parm.num);
                                } else
                                        sprintf(cbuf, "%02d;EAZ%s\n", (int) a,
                                                c->parm.num[0] ? c->parm.num : (u_char *) "0123456789");
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        }
                        break;
                case ISDN_CMD_CLREAZ:
                        if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                                return -ENODEV;
                        if (card->leased)
                                break;
                        if (c->arg < ISDNLOOP_BCH) {
                                a = c->arg + 1;
                                if (card->ptype == ISDN_PTYPE_EURO)
                                        sprintf(cbuf, "%02d;MSNC\n", (int) a);
                                else
                                        sprintf(cbuf, "%02d;EAZC\n", (int) a);
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        }
                        break;
                case ISDN_CMD_SETL2:
                        if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                                return -ENODEV;
                        if ((c->arg & 255) < ISDNLOOP_BCH) {
                                a = c->arg;
                                switch (a >> 8) {
                                case ISDN_PROTO_L2_X75I:
                                        sprintf(cbuf, "%02d;BX75\n", (int) (a & 255) + 1);
                                        break;
#ifdef CONFIG_ISDN_X25
                                case ISDN_PROTO_L2_X25DTE:
                                        sprintf(cbuf, "%02d;BX2T\n", (int) (a & 255) + 1);
                                        break;
                                case ISDN_PROTO_L2_X25DCE:
                                        sprintf(cbuf, "%02d;BX2C\n", (int) (a & 255) + 1);
                                        break;
#endif
                                case ISDN_PROTO_L2_HDLC:
                                        sprintf(cbuf, "%02d;BTRA\n", (int) (a & 255) + 1);
                                        break;
                                case ISDN_PROTO_L2_TRANS:
                                        sprintf(cbuf, "%02d;BTRA\n", (int) (a & 255) + 1);
                                        break;
                                default:
                                        return -EINVAL;
                                }
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                                card->l2_proto[a & 255] = (a >> 8);
                        }
                        break;
                case ISDN_CMD_SETL3:
                        if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                                return -ENODEV;
                        return 0;
                default:
                        return -EINVAL;
                }
        }
        return 0;
}

/*
 * Find card with given driverId
 */
static inline isdnloop_card *
isdnloop_findcard(int driverid)
{
        isdnloop_card *p = cards;

        while (p) {
                if (p->myid == driverid)
                        return p;
                p = p->next;
        }
        return (isdnloop_card *) 0;
}

/*
 * Wrapper functions for interface to linklevel
 */
static int
if_command(isdn_ctrl *c)
{
        isdnloop_card *card = isdnloop_findcard(c->driver);

        if (card)
                return isdnloop_command(c, card);
        printk(KERN_ERR
               "isdnloop: if_command called with invalid driverId!\n");
        return -ENODEV;
}

static int
if_writecmd(const u_char __user *buf, int len, int id, int channel)
{
        isdnloop_card *card = isdnloop_findcard(id);

        if (card) {
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                return isdnloop_writecmd(buf, len, 1, card);
        }
        printk(KERN_ERR
               "isdnloop: if_writecmd called with invalid driverId!\n");
        return -ENODEV;
}

static int
if_readstatus(u_char __user *buf, int len, int id, int channel)
{
        isdnloop_card *card = isdnloop_findcard(id);

        if (card) {
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                return isdnloop_readstatus(buf, len, card);
        }
        printk(KERN_ERR
               "isdnloop: if_readstatus called with invalid driverId!\n");
        return -ENODEV;
}

static int
if_sendbuf(int id, int channel, int ack, struct sk_buff *skb)
{
        isdnloop_card *card = isdnloop_findcard(id);

        if (card) {
                if (!(card->flags & ISDNLOOP_FLAGS_RUNNING))
                        return -ENODEV;
                /* ack request stored in skb scratch area */
                *(skb->head) = ack;
                return isdnloop_sendbuf(channel, skb, card);
        }
        printk(KERN_ERR
               "isdnloop: if_sendbuf called with invalid driverId!\n");
        return -ENODEV;
}

/*
 * Allocate a new card-struct, initialize it
 * link it into cards-list and register it at linklevel.
 */
static isdnloop_card *
isdnloop_initcard(char *id)
{
        isdnloop_card *card;
        int i;
        card = kzalloc(sizeof(isdnloop_card), GFP_KERNEL);
        if (!card) {
                printk(KERN_WARNING
                       "isdnloop: (%s) Could not allocate card-struct.\n", id);
                return (isdnloop_card *) 0;
        }
        card->interface.owner = THIS_MODULE;
        card->interface.channels = ISDNLOOP_BCH;
        card->interface.hl_hdrlen  = 1; /* scratch area for storing ack flag*/
        card->interface.maxbufsize = 4000;
        card->interface.command = if_command;
        card->interface.writebuf_skb = if_sendbuf;
        card->interface.writecmd = if_writecmd;
        card->interface.readstat = if_readstatus;
        card->interface.features = ISDN_FEATURE_L2_X75I |
#ifdef CONFIG_ISDN_X25
                ISDN_FEATURE_L2_X25DTE |
                ISDN_FEATURE_L2_X25DCE |
#endif
                ISDN_FEATURE_L2_HDLC |
                ISDN_FEATURE_L3_TRANS |
                ISDN_FEATURE_P_UNKNOWN;
        card->ptype = ISDN_PTYPE_UNKNOWN;
        strlcpy(card->interface.id, id, sizeof(card->interface.id));
        card->msg_buf_write = card->msg_buf;
        card->msg_buf_read = card->msg_buf;
        card->msg_buf_end = &card->msg_buf[sizeof(card->msg_buf) - 1];
        for (i = 0; i < ISDNLOOP_BCH; i++) {
                card->l2_proto[i] = ISDN_PROTO_L2_X75I;
                skb_queue_head_init(&card->bqueue[i]);
        }
        skb_queue_head_init(&card->dqueue);
        spin_lock_init(&card->isdnloop_lock);
        card->next = cards;
        cards = card;
        if (!register_isdn(&card->interface)) {
                cards = cards->next;
                printk(KERN_WARNING
                       "isdnloop: Unable to register %s\n", id);
                kfree(card);
                return (isdnloop_card *) 0;
        }
        card->myid = card->interface.channels;
        return card;
}

static int
isdnloop_addcard(char *id1)
{
        isdnloop_card *card;
        card = isdnloop_initcard(id1);
        if (!card) {
                return -EIO;
        }
        printk(KERN_INFO
               "isdnloop: (%s) virtual card added\n",
               card->interface.id);
        return 0;
}

static int __init
isdnloop_init(void)
{
        if (isdnloop_id)
                return isdnloop_addcard(isdnloop_id);

        return 0;
}

static void __exit
isdnloop_exit(void)
{
        isdn_ctrl cmd;
        isdnloop_card *card = cards;
        isdnloop_card *last;
        int i;

        isdnloop_stopallcards();
        while (card) {
                cmd.command = ISDN_STAT_UNLOAD;
                cmd.driver = card->myid;
                card->interface.statcallb(&cmd);
                for (i = 0; i < ISDNLOOP_BCH; i++)
                        isdnloop_free_queue(card, i);
                card = card->next;
        }
        card = cards;
        while (card) {
                last = card;
                skb_queue_purge(&card->dqueue);
                card = card->next;
                kfree(last);
        }
        printk(KERN_NOTICE "isdnloop-ISDN-driver unloaded\n");
}

module_init(isdnloop_init);
module_exit(isdnloop_exit);